In mass spectrometry, multiple radio frequency (“RF”) components may be used. Examples of radio frequency components used in a mass spectrometer include ion guides, mass filters, and ion traps. Such RF components may be implemented using a quadrupole configuration. Some mass spectrometers use radio frequency components in tandem or adjacent to one another. The close proximity of these components results in RF coupling between the components. Such RF coupling can be more pronounced in systems that do not use lenses or other intervening components between RF components. This RF coupling causes unwanted perturbations from an adjacent RF component on the other RF component. As a result of these external perturbations, the system performance of the mass spectrometer is degraded. For example, external perturbations on a mass filter as a result of RF coupling with an adjacent RF component results in the mass selectivity of the mass filter to shift. This results in the mass filter passing undesired ions through the system, which degrading the results. In addition, adjacent RF components used in mass spectrometers are particularly prone to RF coupling because of the use of high power RF signals.
One solution to reduce RF coupling between components includes rotating the RF components along a shared central axis with respect to one another to minimize the RF coupling between the components. But, this solution degrades the performance of a mass spectrometer because rotating the components with respect to each other creates a mismatch between the exit ion pattern of the first RF component and the entrance acceptance field of the second RF component.
Another solution is to use high voltage, physically attached capacitors between the two adjacent RF components. The high voltage, physically attached capacitors aid in the suppression of the RF coupling between the RF components. However, inconsistencies between the high voltage, physically attached capacitors because of manufacturing tolerances limit the effectiveness of this solution. These inconsistencies in the values of capacitors result in the high voltage, physically attached capacitors not properly reducing the RF coupling as desired. Moreover, changes in capacitance as a result of temperature variations and other operating conditions of a mass spectrometer also reduce the effectiveness of high voltage, physically attached capacitors effectiveness at reducing RF coupling between components. Other problems with using high voltage, physically attached capacitors between RF components to reduce RF coupling between the components include how to mount and connect the capacitors in the mass spectrometer without negatively changing ion flow or other characteristics of the system. Moreover, the use of high voltage, physically attached capacitors is disadvantageous in that the cost of the capacitors significantly adds to the cost of the RF components.